Auditory, visual, and auditory-visual perception of vowels by hearing-impaired children.

The vowels (foreign letters in text) were presented through auditory, visual, and combined auditory-visual modalities to hearing-impaired children having good, intermediate, and poor auditory work-recognition skills. When they received acoustic information only, children with good word-recognition skills confused neighboring vowels (i.e., those having similar formant frequencies). Children with intermediate work-recognition skills demonstrated this same difficulty and confused front and back vowels. Children with poor word-recognition skills identified vowels mainly on the basis of temporal and intensity cues. Through lipreading alone, all three groups distinguished spread from rounded vowels but could not reliably identify vowels within the categories. The first two groups exhibited only moderate difficulty in identifying vowels audiovisually. The third group, although showing a small amount of improvement over lipreading alone, still experienced difficulty in identifying vowels through combined auditory and visual modes.